problem using jar files in eclipse applications

[Simon]

Hi,

I am trying to use some classes in external jar files. I have no
problem using them in a regular java project developed by eclipse.

The problem is that, I am using EMF (eclipse modeling framework) for a
project developing. "project.editor" can be generated by EMF directly
and then ran "Eclipse Application". Although I set the jar files as
external jars for that "Eclipse Application", it still cannot load
those classes when it runs.

Does anyone know how I can fix this?
Thanks!

-Simon